Thank you @Stennie_X for pointing out. But when i check the same for mongod also the same difference i see.
db.serverBuildInfo() is helpful but i dont see any difference between 3.6.17 CentOS7 and 8.
We have been hitting mongo SECONDARY members getting into hung state and opened a JIRA (https://jira.mongodb.org/browse/SERVER-54805). But we are trying to understand why its happening only with CentOS8. CentOS7 with the same mongo version 3.6.17 is working great. So trying to analyze from all the angle seeing a ldd difference. So thinking if that could cause any issues.